The invention relates to an injector cap for an ampoule support. In particular, the invention relates to the field of so-called injection “pens”, i.e., pen-like injectors or injection devices such as are used for hypodermally administrating medicines, for example for administering insulin for diabetics. The application claims the priority of German patent application No. 100 09 814, filed on Mar. 1, 2000 with the German Patent and Trademark Office.
Basically, injection pens comprise an ampoule support on which a cannula support comprising a cannula is arranged on a facing side. A cap is fastened over the cannula or needle, said cap in its basic state completely hiding the cannula or needle. From this position, the cap can be retracted in the direction of the ampoule support, wherein the cannula emerges from a hole formed on the front facing side of the cap. It is therefore possible to place the pen on the skin, press on it such that the cap slides backwards against a spring force, administer the injection and remove the pen again, wherein the spring force ensures that the cap is returned to its initial position and the needle is hidden again. In this way, a user can administer the injection without ever even seeing the needle, which is particularly advantageous when patients who have phobias or aversions to needles are reliant on such treatments. Moreover, the cap protects the cannula from contamination.
A “pen” is known from U.S. Pat. No. 5,609,577 in which the cap can only be retracted once a holding mechanism is twisted up against a spring force. A disadvantage of the pen disclosed in the '577 patent and other conventional injectors is that the cannula can easily be exposed again after the injector has been used. This creates the danger that a cannula which is no longer sterile is used a second time and so causes inflection. Furthermore, such an exposed cannula can cause injury and transmit diseases, which in the age of Aids can be life-threatening.